Contribution of 18F-FDG PET/CT to Staging of Head and Neck Malignancies

PET Imaging for Head and Neck Cancers

Head and neck cancers are commonly encountered cancers in clinical practice in the United States. Fluorine-18-fluorodeoxyglucose (¹⁸F-FDG) PET/CT has been clinically applied in staging, occult primary tumor detection, treatment planning, response assessment, follow-up, recurrent disease detection, and prognosis prediction in these patients. Alternative PET tracers remain investigational and can provide additional valuable information such as radioresistant tumor hypoxia. The recent introduction of ¹⁸F-FDG PET/MR imaging has provided the advantage of combining the superior soft tissue resolution of MR imaging with the functional information provided by ¹⁸F-FDG PET. This article is a concise review of recent advances in PET imaging in head and neck cancer.

PET/CT in the Evaluation of Hypoxia for Radiotherapy Planning in Head and Neck Tumors: Systematic Literature Review

PET/CT combines imaging at the molecular level along with imaging at the anatomic level, which, with the administration of a hypoxia-sensitive radiopharmaceutical, allows evaluation of tissue oxygenation. Methods: This work consisted of a systematic literature review that included websites, books, and articles dated from July 1997 to December 2019. The aim was to identify the PET radiopharmaceuticals best suited to the detection of cell hypoxia and to recognize the benefits for planning intensity-modulated radiation therapy (IMRT) and volumetric arc therapy (VMAT). Results: Hypoxia affects the likelihood of cure for head and neck tumors, reducing the success rate. Radiopharmaceuticals such as ¹⁸F-fluoromisonidazole, ¹⁸F-fluoroerythronitromidazole, and ¹⁸F-HX4 (¹⁸F-3-fluoro-2-(4-((2-nitro-1H-imidazol-1-yl)methyl)-1H-1,2,3-triazol-1-yl)propan-1-ol) allow the delineation of hypoxic subvolumes within the target volume to optimize IMRT/VMAT. Conclusion: Identification of hypoxic areas with PET/CT imaging and use of subsequent IMRT/VMAT allows for possible escalation of radiation dose in radioresistant subvolumes, with a consequent decrease in relapses and an increased likelihood of disease-free survival.

The Predictive Value of Proportional Evaluation Based on the Metabolic Activity of Cervical Lymph Nodes on PET/CT Imaging in Patients with Larynx Cancer

Objectives

We aimed to evaluate the proportional values of maximum standardized uptake value (SUV_max) for cervical lymph nodes on ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) for prediction of the presence of metastasis in patients with larynx squamous cell cancer (LSCC).

Methods

This retrospective study involved 43 patients with LSCC. All patients underwent resection of the primary tumor and neck dissection within 4 weeks after undergoing ¹⁸F-FDG PET/CT examinations. Receiver operating characteristic (ROC) analysis was performed to evaluate the lymph node SUV_max/primary tumor SUV_max (SUV_maxLN/SUV_maxPT), lymph node SUV_max/aortic SUV_max (SUV_maxLN/SUV_maxA), and lymph node SUV_max/ liver SUV_max (SUV_maxLN/SUV_maxL) ratios for diagnosis of lymph node metastasis.

Results

SUV_maxLN/SUV_maxA, SUV_maxLN/SUV_maxL, and SUV_maxLN/SUV_maxPT rates were significantly higher in metastatic lymph nodes compared to non-metastatic nodes. ROC analysis for metastasis showed that the cut-off thresholds were 3.87 for SUV_maxLN; 1.78 for SUV_maxLN /SUV_maxA; 1.08 for SUV_maxLN/SUV_maxL; and 0.36 for SUV_maxLN/SUV_maxPT. The diagnostic sensitivity, specificity and AUC were 83.7%, 77%, 0.856 for SUV_maxLN; 79.7%, 84%, 1.78 for SUV_maxLN/SUV_maxA; 84.1%, 76%, 0.833 for SUV_maxLN/SUV_maxL; and 53.6%, 76%, 0.666 for SUV_maxLN/SUV_maxPT, respectively.

Conclusion

SUV_maxLN/SUV_maxA, SUV_maxLN/SUV_maxL, and SUV_maxLN/SUV_maxPT ratios can be safely used for diagnosis of cervical lymph node metastasis in patients with LSCC.

A case series on the conservative management of the bony skull in patients with aggressive skin carcinomas of the scalp

Few studies examine techniques of surgical resection for scalp malignancies to ensure clear margins. We present a case series utilizing outer cortex removal in patients without evidence of bony or pericranial invasion. A retrospective casenote review is presented of three cases treated in a tertiary Head and Neck Cancer Centre. An outer table removal approach was utilized based on the absence of bony involvement either on pre-operative imaging or from intra-operative findings. All cases underwent an outer table drilldown procedure. Tumour histology included high grade carcinoma of unknown origin, malignant cylindroma and squamous cell carcinoma. Complete excisions with adequate deep margins were achieved in 100% cases. Overall disease-free survival was 66.6% and local control rate was 100%. This technique allows a high degree of local control, notably at the deep margin. There is little morbidity and it avoids the complications associated with full thickness calvarial resection.